Expansion device



Marchl9, 1929. w-. M. DANN EXPANSION DEVICE Filed April 18. 1922 2 Sheets-Sheet I I/yl II II I) INVENTOR Walter M. Dann.

ATTO'RNEY I I I I I I I I I I I 1 I I I I I I I I I I I I l I I WITNESSES: M

March 19, 1929. w DANN 1,705,721

EXPANSION DEVICE Filed April 1922 2 Sheets-Sheet 2 Fig. 5. 23

27 INVENTOR v WITNESSES:

Walter M. Dann.

BY W A ORNEY Patented Mar. 19, 1929.

UNITED STXTES WALTER M. DAIbTN, 0F WILKINSBURG, PENNSYLVANIA, ASSIQNOBL TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.-

EXI'ANSION DEVICE.

Application filed April 18,

My invention relates to expansion devices and it has particular relation to expansion or conservator tanks employed in' connection with oil-immersed electrical apparatus.

Heretofore, in oil-immersed electrical apparatus great inconvenience and expense has been encountered by reason of the exposure of the insulating oil to the destructive influence of the atmosphere. In such devices, it is necessary to provide means for permitting the insulating oil toexpand and contract, according to the temperature thereof, which is usually accomplished by means of vents or breathers provided for that purpose in the main tank or casing, and Which establish communication between the interior thereof and the outside atmosphere.

When the oil encounters the air admitted to the interior of the tank through the breather, there is a tendency for the same to combine with the oxygen in the air and deteriorate, forming a sludge. The oxygen contained in the air also has a tendency to combine with the gas generated by the chemi cal decomposition or oxidization of the insulating oil and to form an explosive mixture which could cause much damage in the event of a short circuit in the apparatus.

Furthermore, the air admitted through the breather usually contains moisture which mixes with the insulating oil and materially reduces its dielectric ualities.

In order to avoid t e above disadvantages, various devices have been attempted with small success. Dehydrating and conservatortank structures have been successfully employed in certain instances to remove or collect the sludge contained in the oil and the moisture carried in suspension in the air but such devices do not exclude the oxygen contained in the air or prevent the formation 0 the explosive gas above referred to.

One of the objects of my invention is to provide a tank adapted to contain an oilimmersed electrical apparatus and an inert gas and having an expansion tank in communication therewith into which the gas may flow upon the expansion of the insulating oil and which embodies a liquid seal adapted to prevent both the escape of the gas and the possibility of air and moisture from obtaining access to the interior of the casing and coming into contact with the insulating oil.

Another object of my invention is to provide a device of the character set forth which 1922. Serial No. 555,510.

is adapted to be employedin connection with sulating oil.

A still further'object of the invention is to provide a device of the character designated that is simple in construction and'operation and which requires but little, if any, attention.

In the accompanying drawings:

Figure 1 is a sectional view of a portion of a tank and a vertical transverse sectional view of an expansion device constructed in accordgnclei with my invention and connected to the Fig. 2 is a vertical longitudinal sectional view of the expansion device taken on line 11- 11 of Fig. 1. 4

Fig. 3 is a vertical longitudinal sectional view of another form of expansion device.

Fig. 4 is a plan view of another modification of my invention showing its adaptation to use in connection with a plurality of receptacles containing oil-immersed electrical apparatus.

Fig. 5 is a vertical sectional view taken on line VV of Fig. 4.

Referring to the drawings, a main tank 1 is provided with a top portion 2 and is adapted to contain in electrical apparatus such, for example, as a transformer, immersed in insulating oil 3.

An expansion tank, indicated as a whole at 4, is supported by suitable bracket members 5 f which are mounted upon the side of the tank 1 and adjacent to the upper portion thereof.

The tank 4 preferably consists of upper and lower complementary portions 6 and 7, respectively, the adjacent edges of which are provided with outwardly extending peripheral flanges 8. A horizontally-extending plate or barrier 9 is interposed between the portions 6 and 7 of the tank 4, and the parts are welded together along the outer edges of the flanges 8, as indicated at 10.

The tank 4 is thus divided into upper and lower compartments or chambers 11 and 12, respectively, communication between which is established by means of a pipe 13 mounted in the barrier 9 and extending downwardly into the lower chamber 12 to a pomt ad acent to the bottom thereof. A pipe 14 which is mounted in the lower portion of the chamber tions of the main tank 1 and the chamber 12 of the expansion tank 4 and communicating pipes 14 and 15 preferably are filled with an inert gas, such, for example, as nitrogen, which excludes air and prevents the oxidization of the insulating oil and has no tendency to combine therewith to form an explosive mixture.

When the insulating oil 3 in the main tank 1 expands with a rise 1n temperature, the gas contained in the upper portion thereof, together with that contained in the upper portion of the chamber 12, is subjected to pressure which lowers the level of the oil 16 in the chamber 12 and forces a portion thereof vertically through the pipe 13 into the u per chamber 11 of the tank 4 against the orce of gravity. The air contained in the upper chamber 11, displaced by the risin oil level therein, may escape to the outside" atmosphere through a suitable breather or vent 17.

Upon contraction of the oil 3 in the main tank, resulting from a decrease in the temperature thereof, the gas that was forced into the compartment 12 of the tank 4 will be returned to the upper portion of the main tank 1 by reason of the weight of the oil contained in the upper chamber 11 and in the pipe 13 of the expansion tank 4.

In Fig. 3 is illustrated another form of the invention in which the tank 4 is provided with a vertically-extending barrier 18 disposed at substantially the middle thereof, and which divides the interior of the tank 4 into compartments 19 and 20. Communication is established between the compartments 19 and 20 by means of an aperture 21 provided in the lower portion of the barrier 18.

The compartments 19 and 20 are both filled with oil to a level suflicient to seal the aperture 21 in the barrier 18. A pipe 22 is mounted in the lower portion of the tank 4 and ex tends vertically through the co p rtment 19 to a point above the level of the oil therein and establishes communication between the chamber 19 and the upper portion of the main tank 1. The upper portion of the chamber 19, above the level of the oil, is filled with an inert gas. and the upper portion of the chamber 20 is in communication with the outside atmosphere through a breather or vent 23.

When the insulating oil-in the tank 1 expands, it subjects the gas contained in the chamber 19 to ressure which forces the oil contained therein through the aperture 21 in the barrier 18 and into the chamber 20. The air contained in the chamber 20 is displaced by the rise of the oil-level therein and may escape to the outside atmosphere through the vent 23. The result is that when the oil in the chamber 19 is under pressure its level is lowered, with a consequent elevation of the oil-level in the chamber 20, as indicated by the dotted lines in Fig. 3. This difference in the oil-levels in the respective chambers causes a back pressure to be exerted upon the gas in the chamber 19 which balances the pressure exerted by the expansion of the insulating oil in the main tank 1 and causes the return of the gas thereto upon the contraction of the oil contained therein.

In Figs. 4 and 5 is illustrated a still further embodiment of my invention which is particularly adapted for use in connection with a group of main tanks, and in which I construct the expansion device of two separate tanks 24 and 25 disposed in end-to-end and superposed relation and which are secured to ether by means of a band or strap 26. A pipe 27 establishes communication between the lower portions of the tanks 24 and 25, and a breather 28 effects communication between the upper portion of the tank 24 and the atmosphere. A pipe 29 establishes communication between the upper portion of the lower tank .25 and a horizontally-extending pipe 30,

which, in turn, communicateswith a plurality of main tanks 31.

The operation of the above described construction is substantially like that of the devices previously explained. The excess pressure caused by the expansion of the insulating oil in the main tank causes the oil in the tank 25 to be displaced and to flow upwardly, through the pipe 27 into the upper tank 24. The dilierence in the levels of'the two bodies of oil will cause the return of the gas to the maiin tanks when the pressure therein is lowere From the foregoing, it will be apparent that, by employing an inert gas in connection with an oil insulated electrical apparatus, the danger from explosion is avoided and that, by means of my structure, the inert gas may be displaced upon the expansion of the insulating oil and returned to the main tank when the temperature of the oil decreases without permitting any of the gas to escape to the outside atmosphere. Also, by employing an expansion device constructed in accordance with my invention, it will be impossible for moisture-laden air to obtain access to the interior of the tank.

Furthermore, it will be observed that,

should an excess temperature riseoc'cur within the main tank, the heated oil may displace all-of the gas and oil contained in the expansion device and escape without damage to the apparatus.

It will be understood that modifications and variations other than those specifically illustrated and described maybe employed within the scope of my invention and that the utilization of an inert gas is not essential, provided insurance against the formation of explosive gaseous mixtures is not regarded as necessary or particularly desirable.

I claim as my invention:

1. A transformer tank partially filled with insulating liquid and having a body of gas in the space above said liquid, an electrical translating device immersed in said liquid medium, and an expansion tank comprising two communicating compartments having a liquid seal therebetween, one of said compartments having gas therein and communicating with the space in the first mentioned tank and the other of said compartments communicating with the atmosphere whereby the first named ,body of gas serves as a cushion upon sudden changes in the volume of said insulating fluid and a certain amount of said gas may be transferred between the space in the tank. and one compartment without contact with the atmosphere, said electrical translating device, during operation, generating heat to expand said insulating liquid and force gas from said tank into said one of said compartments, said electrical translating device cooling, when operation thereof is discontinued, to permit contraction of said insulating liquid with consequent passage of gas from said one of said compartments to said tank. v

2. A transformer tank partially filled with insulating liquid and having a body of inert gas inthe space above said liquid, an electrical translating device immersed in said insulating liquid, and an expansion tank comprising two communicating compartments having a liquid seal therebetween, one of said compartments having inert gas therein agl communicating with the space in the first mentioned tank and the other of said compartments communicating with the atmosphere whereby the first named body of gas serves as a cushion upon sudden changes in the volume of said insulating fluid and a certain amount of said gas may be transferred between the space in the tank and one compartment without contact with the atmosphere, said electrical translating device, during operation, generating heat to expand said insulating liquid and force inert gas from said tank into said one of said compartments, said electrical translating device cooling, when operation thereof is discontinued, to permit contraction of said insulating liquid said electrical translating device, during opr'ation, generating heat to expand said first named liquid medium and force gas along said path from said casing, said electrical translating device cooling, when operation thereof is discontinued, to permit contraction of said first named liquid medium with consequent passage of gas along said path into said casing.

4. The combination with a casing containing an insulating liquid medium, of an electrical translating device in said liquid medium, a cushion of inert gas within said .casing above the level of said liquid medium, an expansion tank containing a liquid medium, a cushion of gas within said expansion chamber above the level of said second named liquid medium,'and means comprising a communicating path between said gas cushions, said electrical translating device, during operation thereof, generating heat to expand said first named liquid medium and force inert gas along said path from said casing, said electrical translating device cooling,

when operation thereof is discontinued, to

permit contraction of said first named liquid medium with consequent passage of inert gas along said path into said casing.

5. The combination with a casing containing an insulating liquid medium, of an electrical translating device in said liquid medium, a cushion of gas within said casing above the level of said liquid medium, an expansion tank containing a liquid medium, a cushion of gas within said expansion chamber above the level of said second named liquid medium, means comprising a communicating path between said gas cushions, and means comprising a passage opening into said second named liquid medium and open to the atmosphere, said electrical translating device, during operation, generating heat to expand said first named liquid medium and force gas along said path from said casing, said electrical translating device cooling, when operation'thereof is discontinued, to permit contraction of said first named liquid medium with consequent passage of gas along said path into said casing.

6. The combination with a casing containing an insulating liquid medium, of an electrical translating device in said liquid medium, a cushion of gas within said casing above the level of said liquid medium, an expansion tank comprising a plurality of chambers, a liquid medium and an overlying cushion of gas within one of said chambers, means comprising a communicating path between said gas cushions, and means comprising a passage opening into said second named liquid medium and into another of said chambers, said electrical translating device, during operation, generating heat to expand said first named liquid medium and force gas along said path from said casing, said electrical translating device cooling, when operation thereof is discontinued, to permit contraction of said first named liquid medium Withconsequent passage of gas along said path into said casing.

7. The combination with a casing containing an insulating liquid medium, of an electrical translating device in said liquid medium, a cushion of gas Within said casing above the level of said liquid medium, an exansion tank comprising a plurality of chamers, a liquid medium and an overlying cushion of gas Within oneof said chambers, means comprising a passage opening into said second named liquid medium and into another of said chambers, and means for maintaining said second named chamber substantially at atmospheric pressure, said electrical translating device, during operation, generating heat to expand said first named liquid medium and force gas along said path from said WVALTER M. DANN. 

